32 THE EVOLUTION OF SCIENCE. 



nugget of pure silver. Nothing was more natural than 

 to suppose that the lead was transformed into silver ; 

 and to build on this and analogous facts the theory of the 

 transmutation of the metals, a theory which, later on, led 

 to the search for the philosopher's stone." The alchem- 

 ists, therefore, were carried to fruitless conclusions, not 

 by anything wrong in their experiments or their logic ; 

 but their minds were driven in a wrong direction by a 

 false motive. They were not in search of truth ; we need 

 not wonder that they missed finding it. 



Having thus pointed out the contrast in their motives, 

 we may next proceed to show that alchemy was a life- 

 less mass of chemical operations, while chemistry was a 

 living body of natural science. 



Alchemy, according to M. Hofer, arose in the fourth 

 century of our era. It flourished twelve hundred years. 

 In the sixteenth century its transformation into real 

 chemistry began, and the last traces of it vanished less 

 than one hundred years ago. 



There is an erroneous idea — I do not know how widely 

 it prevails — that alchemy ought to be credited with all 

 the chemical knowledge which had been acquired pre- 

 vious to the revival of learning in the sixteenth century. 

 The fact is, however, that a large part of this knowledge 

 is more ancient than alchemy ; and the true value of 

 alchemy as a step toward chemistry is represented by 

 the residue. 



From the ancients the alchemists inherited various 

 processes with the furnace and the blowpipe : methods 

 of extracting several metals from their ores ; the art of 

 making colors, of enameling metals, of tanning hides, of 

 glassmaking, together with a knowledge of several val- 

 uable alloys, salts, and other chemical jjroducts. Now, 

 during the twelve hundred years of alchemy, these val- 

 uable arts were stationaiy. The sum of chemical 

 knowledge was enlarged during that interval only by 



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